Water - Safe to Drink? Nepal
Mwamongu Village water source, Tanzania
Water source in Dar es Salaam, Tanzania
The presence of the bacterium Escherichia coli indicates recent fecal contamination of water.
Water tests should provide this information
Components of the Portable Microbiology Laboratory with Colilert and Petrifilm tests for E. coli
Old, inexact methods on the left, to be replaced by modern tests for E. coli, right
Portable Microbiology Laboratory. Materials for 25 water tests in gallon-sized plastic bag
Prof. Metcalf holds the two Portable Microbiology Laboratory tests: Colilert MPN tube, and E. coli count Petrifilm.
Colilert: A presence/absence test for E. coli in bottles or tubes
Colilert for 100 ml, left, and 10 ml, tubes on right.
Colilert is an approved water testing method in 40 countries
ONPG and MUG are the two substates for E. coli in Colilert
How to use Colilert MPN. Collect water in sterile WhirlPak (open well in Temeke Municipality, Dar es Salaam, Tanzania)
Carefully remove cap from Colilert tube
Use sterile pipette to add 10 ml of water source
Carefully replace cap
Shake tube to dissolve chemicals
Incubate tubes at 35°C for next day results
Tubes can also be incubated next to one's body to obtain next day results.
Body incubation of Colilert tubes
Next day Rresults Clear = no coliform bacteria. Yellow (ONPG+) = coliform bacteria present, possibly E. coli
Use a battery-operated long UV light to shine on tubes. Blue fluorescence = MUG +, E. coli is present, water not safe to drink.
The best test for E. coli in foods: E. coli Count Petrifilm
Two substrates in Petrifilm for E. coli, lactose and BCIG
To use Petrifilm, label sample source and time
Use sterile pipette to collect exactly 1 ml of water
Raise the edge of film to expose nutrient circle
Add 1 ml of water sample to nutrient circle
Carefully roll down film onto nutrient circle
Use flat side of plastic spreader to gently distribute 1 ml over entire circle
Petrifilms ready for incubation
Petriflms covered with firm cardboard enables incubation on one's body, ~20 doublings for invisible bacteria to develop into visible colonies
Results usually in 10-18 hr. E. coli = blue colonies with gas. Coliforms besides E. coli = red with gas.
Petrifilm & Colilert tests correlate with risk of disease, WHO Guidelines for Drinking Water Quality, 2nd Edition.
UN Habitat Water Testing Booklet, November, 2010
Ready to start workshop. Boniphace translates for Prof. Metcalf
Two water sources in Saka Saka. From a pump (green bucket) and an open stream (yellow bucket).
Adults will sample either pump or stream water
Mixing inoculated Colilert tubes, to incubate overnight
Petrifilms also inoculated by either pump or stream water
Next day demonstration of solar cooking, solar water pasteurization
Next day results: Pump water yellow, MUG -, no E. coli. Stream yellow and MUG+, E. coli present.
Examining Petrifilms the next morning
Next day Petrifilm results are clear.
Stream water (front) with ~100 E. coli colonies on each Petrifilm, very high disease risk. Pump water with coliform bacteria, but not E. coli, low disease risk.
All villagers see results of grossly contaminated stream water, no E. coli contamination of pump water.
Solar cooked rice in 2 hr
Providing a year's supply of water testing materials to Saka Saka health workers
Solar water pasteurization and cooking demonstrated in Saka Saka. This could be replicated in villages worldwide.
Water testing/solar pasteurization workshop for Village Chiefs and Village Health workers, Meatu District, Tanzania, 2001
Village health workers examine results the following day
Village chief knows that MUG+ Colilert means that E. coli was in the town's river water source, unsafe water
Health worker finds >10 E. coli on Petrifilm, town river source poses a very high risk of disease
Boniphace explaining Petrifilm results of village water sources Meatu
Workshop participants given Colilert tubes to test home water sources, Nyakach, Kenya, 2003
Colilert tubes incubated overnight in Nyakach
All home water sources ONPG +, contain coliform bacteria
All water sources from shallow wells also contain E. coli
Collecting Nyakach shallow well water for testing
Results of Nyakach shallow well - > 10 E. coli/ml very high risk of disease
Students at California State University, Sacramento, who contributed to water pasteurization work
Water Pasteurization article, 1984
Water Pasteurization Indicator (WAPI). When water reaches 65°C (149°F), wax melts and falls to the bottom. Water is pasteurized.
Use a Cookit solar cooker. 5 liters pasteurized in 3 hours of sunshine
Article on Cookit and WAPI to pasteurize water, 1999
Water vendor collecting river water, Mwanhuzi town, Meatu District, Tanzania, 2000
Water vendors try to sell water in Mwanhuzi
Guest House (hotel)
River water provided for guests
After testing river water, collect for solar pasteurization
Heating river water in Cookit
Temperature >60°C in 2 hours
WAPI wax melted, water is pasteurized
Ready to test pasteurized water
Micro tests before (top) and after solar pasteurization
Solar cooking & solar water pasteurization in Nyakach, Kenya
Solar cook in Nyakach with WAPI
Africa Women and Water Conference, Nairobi, July, 2008
Water testing session
Inoculating Petrifilms and Colilert tubes with water from their home areas
Next day results of Nigeria water
Examining Petrifilm results
Prof. Metcalf shows 2004 Nobel Peace Prize winner Prof. Wangari Maathai Colilert test results
And Petrifilm results
In Bondo, Kenya, With Laban Onongno, UN-Habitat Chief Technical Advisor, Lake Victoria Wat/San Program
Prof. Metcalf leads workshop for Bondo community, December, 2008
Inoculating Colilert test with 10 ml of Bondo drinking water source
Petrifilm test of Bondo drinking water source
Next day results in Bondo
Now we're microbiologists!
Results from nine Bondo water drinking water sources
PML methods taught in Bondo by Gobei Secondary School teacher Tobias Amolo, July, 2009
Prof. Metcalf presents PML materials to Mr. Amolo, July, 2009
Class results of local water sources before and after WaterGuard treatment.
Test results before and after chlorination of water source
UN-Habitat workshop in Kisumu, Kenya, July, 2010
UN-Habitat water testing workshop, Harar, Ethiopia, November, 2010
World Water Congress, Montreal, Sept 19-23, 2010
IWHA sponsorship of booth at World Water Congress
Booth table becomes a laboratory
PML to Zimbabwe
Poster at World Water Congress
World Water Week, Stockholm, Sweden, August 20-26, 2011
UN-Habitat booth. Demonstrating water testing.
Portable Microbiology Laboratory for World Vision, Ghana
Prof. Metcalf and UN Habitat's Lars Stordal at Rwanda workshop location
Each workshop participant received a mini-PML, materials for 10 water test, and a WAPI